Conventionally, photographically useful reagents which are sparingly soluble in water, [for example oil soluble couplers, anti-color fading agents or anti-color mixing agents which are used to prevent the occurrence of color fading, color fogging or color mixing (for example alkylhydroquinones, alkylphenols, sulfonamidophenols, dye diffusion type couplers, chromans, coumarones etc.), film hardening agents, oil soluble filter dyes, oil soluble ultraviolet absorbers, brightening agents, DIR compounds (for example DIR hydroquinones, colorless DIR couplers etc.), developing agents, dye developing agents, DDR redox compounds, DDR couplers, etc.] have been dissolved in a suitable high boiling point solvent and then dispersed in the presence of a surfactant in a solution of a hydrophilic organic colloid, especially gelatin, and they have been used in this state by inclusion in hydrophilic organic colloid layers (for example in photosensitive emulsion layers, filter layers, backing layers, antihalation layers, intermediate layers, protective layers etc.). Special use has been made of phthalate ester based compounds and phosphate ester based compounds as high boiling point organic solvents.
The phthalate ester based compounds and phosphate ester based compounds which are used as high boiling point organic solvents are excellent in respect of the dispersibility of the coupler, their affinity with colloid layers such as gelatin layers, their effect on the stability of the color image, their effect on the hue of the color image, their chemical stability in photosensitive materials, and in respect of the fact that they can be acquired cheaply, and they have been widely used in the past.
However, the known high boiling point organic solvents (for example the phthalate ester based compounds and the phosphate ester based compounds) are inadequate in respect of preventing the occurrence of stain and fading of the colored image due to light, heat and moisture in the latest photosensitive materials where high performance is required. Furthermore, there are cases where these high boiling point organic solvents are not satisfactory for achieving the preferred hue in the colored image, and there is a need for novel high boiling point organic solvents.
Furthermore, attention has focused on the problem of post processing stain (stain on the background) in view of the marked progress which has been made with the simplification and speeding up of the development process, as typified by the use of two bath processing which consists of a color development process and a bleach-fix process, and reduction in the amount of washing water, etc.
It is thought that some stain (so-called process stain) occurs as a result of aerial oxidation or oxidation during the bleach or bleach-fixing process of developing agents (p-phenylenediamine derivatives) which remain in the photosensitive material after color development with the formation of oxidized forms which react with the residual couplers, and some means of countering this effect is required.
On the other hand, the high boiling point organic solvents must themselves be sufficiently stable in respect of heat, light and moisture in order to prevent color fading of the colored image and stain on the background (stain) due to heat, light and moisture, and, in general, hydrocarbons of low polarity have been suggested for realizing these objectives.
For example, aromatic hydrocarbons such as t-butylbenzene have been proposed in JP-A-49-90523 (the term "JP-A" as used herein signifies "unexamined published Japanese patent application"), paraffins have been proposed in JP-A-54-99432, and unsaturated hydrocarbons such as 1-dodecene and t-butylbenzene have been proposed in JP-A-59-133545 and JP-A-59-137952. However, the solubility of photographically useful additives, such as couplers etc., which generally have polar structures within the molecule in these high boiling point organic solvents of low polarity is poor, and sometimes the solubility is inadequate, while on other occasions problems arise with poor dispersion stability and precipitation, etc.
The chlorinated paraffins disclosed in JP-A-61-84641 provide improved solubility and dispersion stability, but even so they still have an inadequate effect in respect of preventing the occurrence of staining and fading of a color image.
Further, the carboxylic acid esters and amides which contain fluorine substituted alkyl groups disclosed in JP-A-53-146622 (for example 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl hexanoate and N,N-diethyloctafluoropentanamide) have an inadequate effect in respect of the occurrence of staining and fading of a color image and, moreover, there are problems with solubility and low dispersion stability which are thought to be due to the oil repelling properties which are a distinguishing feature of fluorocarbons.